grad, gress = step

aggressive (adj) hostile; pushy; stepping into someone's space with   forceful energy

centigrade (adj) Celsius; temperature rating on the thermometer made up of 100 degree intervals or steps between the freezing and boiling points of water

degrade (v) to reduce someone's worth or value; to make someone step down to a lower position or rank; to move down a step in social status

digress (v) to stray away from the main topic; to step away from the topic and lose clarity; to wander in thoughts or ideas

gradual (adj) a slow change; a step-by-step change

graduate (v) to move up a step in education (usually out of a school)

progress (v) to move a step in a positive direction; to improve; to move a step closer to a goal

progression (v) a step-by-step sequence within a continuous series

regress (v) to go back; to move backward; to move a step back

upgrade (v) to move up a step change or level; to improve in quality